1. Field of the Invention
The present invention relates to an elastic supporting structure for an optical image stabilizer and, more particularly, to an elastic supporting structure for preventing a lens module from permanent deformation should the lens module be dropped, thereby providing the lens module with enhanced shock resistance.
2. Description of the Prior Art
Digital cameras have been continuously downsized due to the advancement of technology, and thanks to the miniaturization of lens modules, many small electronic devices nowadays, such as mobile phones, are equipped with digital camera functions as a basic requirement. In order to provide automatic focusing or zooming, the microlenses in those electronic devices are typically driven to move by a voice coil motor (VCM), which carries a lens and can move the lens back and forth along an image-capturing optical axis by means of a coil, a magnet and an elastic plate. Moreover, consumers have had higher and higher requirements for image quality and camera functions, and it is such advanced criteria as a 10-megapixel resolution and anti-shake systems that distinguish high-end cameras from low-end ones.
In an optical system composed of a lens module and an image compensation module, e.g., the optical system of a still camera or a video camera, the optical path tends to be shifted because of external factors or as a result of the shaking of the hand holding the camera. Should the optical path be shifted, imaging of the image compensation module will become unstable such that the images captured are blurred. The most common solution is to provide a compensation mechanism for the image blurring phenomenon caused by shaking, wherein the compensation mechanism, either digital or optical, serves to clarify the images captured.
The so-called digital compensation mechanism refers to analyzing and processing the images captured by the image compensation module so as to obtain clearer digital images. This approach is also known as the digital anti-shake mechanism. The optical compensation mechanism, on the other hand, refers to providing a vibration compensation device either on an optical lens set or on the image compensation module, and this approach is also known as the optical anti-shake mechanism. The existing optical anti-shake mechanisms typically involve complicated or bulky mechanisms or components and are therefore disadvantaged by technical complexity, difficulty of assembly, high costs, or undesirably large volumes that cannot be further downsized. In short, the known optical anti-shake mechanisms leave room for improvement.
FIG. 1 is a schematic view of the optical compensation mechanism disclosed in Japanese Patent Application Laid-Open No. 2002-207148. As shown in the drawing, the circuit substrate 301a of the image sensor 300a is supported by the flexible elements 400a to 403a, which are made of metal wires and can move perpendicular to the optical axis 201a. The X-axis and Y-axis displacements of the lens element 203a (which includes the lens 200a and the lens holder 202a) relative to the circuit substrate 301a are detected by the two relative displacement sensors 500a, 501a and the displacement detector 503a and sent to the anti-shake controller 504a so that, under the control of the anti-shake controller 504a and according to the detected displacements, the driving element 502a drives the circuit substrate 301a into corresponding movements perpendicular to the optical axis 201a, thereby preventing the image sensor 300a from generating blurred images which may otherwise result from the shaking of the image sensor 300a. 
However, the mechanism proposed by the afore-cited Japanese Patent Application Laid-Open No. 2002-207148 for preventing shake-induced blurred images is only conceptual. The invention disclosed in the present application is based on a similar concept but is further incorporated with an automatic focusing module, wherein not only is resistance provided against shake-induced lateral shifting along the X axis and the Y axis, but also the lens element, when dropped, is protected from permanent (e.g., plastic) deformation in the Z-axis direction (i.e., along the image-capturing optical axis). In other words, enhanced resistance is provided against shakes resulting from the drop impact.